Ebooks
What is a PDB file?
Updated Jul 2026
PDB (Palm Database) is an ebook format built for Palm OS devices back when Palm Pilots and similar handhelds were the main way people read ebooks on the go. It stores plain text losslessly, with no quality loss, but its formatting is basic and almost no modern e-reader or app opens it directly.
- Extension
- .pdb
- Type
- Ebooks
- Typically
- Palm / legacy readers
Why PDB exists
PDB started out as a general-purpose database container on Palm OS, the operating system that ran Palm Pilots and other handheld organizers in the late 1990s and early 2000s. Ebook readers of that era, like Palm Reader and various Doc readers, repurposed the format to hold book text, and PDB ebooks became common long before Kindle or EPUB existed.
Under the hood a PDB ebook is just compressed text broken into small records, plus a bit of structure so a reader app can jump to any page quickly. That simplicity is why it survived on low-power handheld hardware, but it also means PDB has little room for the layout, images, or styling that later formats like EPUB handle easily.
Most people run into a PDB file today because they're digging through an old ebook collection, a backup from a Palm device, or files downloaded from an early ebook site. Since current e-readers, phones, and tablets don't recognize PDB, the file needs converting to something like EPUB or MOBI before it will open anywhere.
The trade-offs
Strengths
- Stores text losslessly, so nothing is lost from the original wording
- Very small file size, suited to old low-memory devices
- Simple structure that's been stable and readable for decades
Watch-outs
- Not supported by modern e-readers, phones, or reading apps
- Limited formatting: little support for images, fonts, or complex layout
- Needs converting to EPUB or a similar format before you can read it today
A note on privacy
A PDB ebook doesn't usually carry personal metadata the way a photo does, but it can still be a private file, an old journal, personal notes, or a book you'd rather not hand to a stranger's server. Uploading it to a web-based converter means that file sits on someone else's system, even briefly. Converting it on your own computer keeps the whole thing local from start to finish.
Questions
How do I open a PDB file?
Modern phones, tablets, and e-readers don't open PDB natively, so you'll generally need to convert it to EPUB or MOBI first. Once converted, it opens in any standard reading app.
Is PDB better than EPUB?
Not for reading today. PDB is a much older, simpler format with limited formatting, while EPUB supports rich layout, images, and works across nearly every current device. PDB mainly matters if you already have old files in that format.
Why do I have PDB files on my computer?
They usually come from an old Palm OS device, a backup of one, or ebooks downloaded years ago before EPUB and Kindle formats took over. Finding them in an old folder or backup is the most common reason people encounter PDB now.
Can I convert a PDB file without uploading it?
Yes. A desktop app like Morphjet converts PDB to EPUB or another modern format directly on your computer, so the file never has to leave your machine.
Morphjet opens and converts PDB and 1,800+ other formats, all on your own computer. Launching this July.